Just thinking about how IPv6 uses 128 bits to identify a host & network, while a MAC address is only 48 bits. Wouldn't it make sense to just use the MAC address as the host portion of an IP address? Then the 80 other bits can be used for network. Maybe the first 8 bits for country, then some for state/province, then county, then city. I know some organizations have multinational so maybe something different.